This invention relates to a machine for cleaning or otherwise treating floors and other work surfaces formed of carpet, tile, wood and other materials. The most efficient and effective surface treatments employ a vibration, “scrubbing”, motion to loosen materials on the work surface and within any permeable material, such as a rug or other fabric, under or part of the work surface. On floors and other work surfaces, a machine typically uses a cleaning towel, “pad”, in combination with a solvent, including water or steam, and/or a cleaning agent. Removal of some stains or other material is sometimes better achieved without a solvent or cleaning agent. When the cleaning towel scrubs the floor and becomes dirty, the towel is replaced with a clean one. The machine is easier to use when automatic drive forces are generated in or by the machine.
Important attributes of surface treating machines are cleaning effectiveness, ease of use, convenience, stability, light weight, low machine wear, long life and ease of maintenance. These attributes are import for machines used by professionals in heavy duty environments or used by other consumers in home or other light duty environments.
Cleaning effectiveness requires that machines include a small oscillation that creates a local vibration in a cleaning plate and cleaning pad to impart a “scrubbing” movement to the surface being treated. For cleaning floors, the local vibration is preferably in a range of several millimeters. Cleaning effectiveness and convenience frequently requires that the shape of the cleaning plate be rectangular so as to be readily used along straight edges and easily moved into rectangular corners. In order to satisfy these attributes, machines with round bottom plates are often undesirable.
Ease of use and convenience require stability, appropriate size and weight and ease of operator control. Designs that position the motor and drive assembly high above the cleaning plate are undesirable since such configurations tend to excessively accentuate vertical instability. Vertical instability results in unwanted oscillation of the cleaning plate up and down in a mode that is in and out of the plane of the work surface. The plane of the work surface is referred to, for example, as the floor surface plane or the XY-plane. Excessive vertical instability is distinguished from horizontal oscillations providing local vibration to impart a “scrubbing” movement to the cleaning plate. The horizontal oscillations are parallel to the plane of the work surface, that is, parallel to the XY-plane. Vertical instability is additionally undesirable because it uses excessive amounts of energy, reduces the energy efficiency of the machine and causes increased wear on the motor, the drive shafts, the drivers and the drive bushings. The increased wear increases maintenance and decreases the life of the machine. User fatigue is dramatic when unwanted vertical oscillations occur.
High energy efficiency is an important attribute. For machines powered by an AC electrical service through an AC-to-DC converter or powered by a battery, the size and cost of the motor is a function of the energy requirements needed to drive the transmission and the cleaning plate. For DC motors, the energy requirements are important for the motor and for the AC-to-DC converter used to convert the AC electrical service to DC. The more energy efficient the machines, the smaller and less expensive are the AC-to-DC converters, batteries and motors required to power the machines.
Another factor in cleaning effectiveness is determined by the material of the machine in contact with the floor material. Brushes are effective in loosing material but are not absorbent and therefore are inefficient in removing solid and liquid matter from a floor. For existing machines that use a towel, the towels are typically synthetic and do not absorb and hold solid and liquid matter from a floor. For towels that are primarily cotton, they have the disadvantage of not scrubbing well and also have high friction with the floor surface resulting in low energy efficiency.
Another factor in cleaning effectiveness is determined by the ease of driving the machine across the cleaning surface. Driving the machine is a function of (i) the driving force of the machine, (ii) the surface characteristic of the pad and (iii) the surface characteristics of the floor or other surface over which the pad moves; and (iv) the weight of the machine and hence the cleaning area/weight ratio of the machine.
A desirable feature of a machine allows the handle to extend close to the floor so as to easily fit under furniture. Similarly, battery placement in the handle allows for ease of operation under furniture.
In light of the above background, it is desirable to have improved surface treatment machines for treating carpets, tiles, wood and other surface materials.